[G0] Gate: certify core ingest-read-chat journey reliable

[dkritarth]

Gate purpose

Phase 0 closes only when Vellum's core value proposition works through Codex in running Electron app. Closing this issue unlocks Phase 1.

Dependencies

Blocked by #25, #26, and #27, plus every blocker bug discovered by #26. Do not close while any linked blocker remains open.

Exit criteria

• Codex signed-in ACP smoke is repeatably green.
• Real paper ingests and re-ingests without corruption or duplicate row.
• Paper appears in Library and opens in reader.
• Reader navigation/search/zoom/TOC work in live app.
• Summary and Details match source paper at spot-checked points.
• Ask returns streamed, paper-grounded response through Codex.
• Chat and other existing durable state survive restart.
• Core E2E harness is green.
• Full tests, typecheck, build, and diff check pass.
• Console has no unexplained errors/warnings.
• All S0 blocker issues are closed with PR evidence.

Gate review method

A reviewer other than implementation agent re-runs core journey from isolated state and posts results. Only after review may maintainer close gate and relabel first Phase-1 issue from status:blocked to status:ready.

Non-goals

This gate does not certify later notes, selection, annotation, citation, collection, or cross-paper workflows.

Required PR evidence

PR must use Closes #28, remain focused on this issue, and include:

• failing test or reproducible baseline before behavior changes;
• focused and full automated results;
• npm test, npm run typecheck, npm run build, and git diff --check;
• exact live Electron steps and observed results;
• screenshots for visible UI changes when tooling permits;
• console errors/warnings and unresolved limitations;
• real-paper or signed-in ACP evidence where applicable.

Mocks prove code paths only. They never prove Electron integration, persistence across restart, PDF rendering, or signed-in ACP behavior.